As known well, the robot traveling on the wall has been widely utilized for performing works, such as cleaning, inspection and coating of the wall of the construction including building, bridge and tunnel, whose completion has conventionally required even the experienced worker to face the danger. As this kind of robot traveling on the wall, for example, the robot is found in the disclosure by Japanese unexamined patent application No. SHO (64)-5798.
The afore-mentioned disclosure is concerned with the liquid jet shutoff unit mounted to the robot traveling on the wall. This used robot can be traveled on the wall by means of a pair of crawler type traveling vehicles having a plurality of adsorption discs formed on the crawler surface and the suction force generated from them is subject to negative pressure which takes place in the space formed among the adsorption discs and the wall under the principles of jetting the compressed air, supplied by way of piping from compressor, from ejector.
Japanese unexamined utility model registration application No. HEI (01)-128475 and Japanese unexamined utility model registration application No. HEI (04)-38386, for example, disclose the movable adsorption disc used for the robot traveling on the wall.
The former application is concerned with improvements in the adsorption disc of the crawler type robot capable of moving on the wall and is characterized by disposing inducing suction part in the adsorption disc, the inducing suction part aiming specifically at a promotion of efficiency at the suction process performed just before a touch of the adsorption disc to the wall surface.
The latter application discloses an object of providing another adsorption disc easy to absorb as well as attainable to adhere, such merits being fulfilled by constructing the adsorption disc proper out of the hard adsorption disc base made of the hard elastic material and the soft adsorption disc top end made of the soft elastic member.
But, a series of the afore-mentioned applications have debatable points respectively: Namely, the model disclosed by the afore-mentioned Japanese unexamined patent application No. SHO (64)-5798 permits a pair of crawler type traveling vehicles having a plurality of adsorption discs formed on the crawler surface to travel the robot, so in addition to necessity of two units of crawlers, the construction of locating no adsorption disc in a space between the two units of crawlers might reduce the adsorption surface, thereby making the adsorption force weaker.
Both of the movable adsorption discs mentioned in the afore-mentioned Japanese unexamined utility model registration application No. HEI (01)-128475 and Japanese unexamined utility model registration application No. HEI (04)-38386 are constructed to make the adsorption against the wall easy as well as to attain the adherence to the wall constantly, the relative working efficiency being enhanced in the way of these applications, but if these kinds of movable adsorption discs are used for the robot required for traveling on the wall, resulting debatable points lie in easiness of the adsorption disc to be glided on the wall due to wet surface of the wall or the dead weight and in difficulty of putting the same into practical use at the working site simply in spite of being easy to adsorb and/or attainable to adhere constantly.